For precise and/or long manual operations, such as surgical operations and the like, there are known body support apparatuses for supporting a part of an operator's body, such as an arm. Such a body support apparatus is required to make an arm support supporting an operator's arm follow motion of the supported arm, and lock the arm support when the operator wants to fix the supported arm.
In order to meet such requirements, there are known body support apparatuses, an example of which is disclosed in Japanese Patent Application Publication No. 2009-291363, referred to as a first patent application.
The body support apparatus disclosed in the first patent application is configured to switch its operation mode between a lock mode and a free mode according to an operator's operation of a foot switch and/or the level of force; the level of force is applied from the supported arm to the arm support, and is measured by a sensor. In the lock mode, the arm support is locked so that the operator does not move the supported arm. In the free mode, the arm support is freely movable so that the operator freely moves the supported arm.
For example, when the operator moves the supported arm to a desired position, and thereafter weakens force applied from the supported arm to the arm support, the sensor measures the change of the force applied to the arm support. In response to the measured result indicative of the change of the force applied to the arm support, a controller activates a brake to thereby lock the arm support to the desired position.
On the other hand, there is known a technology that indicates whether an operation lever for stopping motion of a bendable portion of an endoscope is locked or not, an example of which is disclosed in Japanese Patent Application Publication No. H09-173279, referred to as a second patent application.
In the second patent application, an indicator, which indicates whether the operation lever is locked or not, is provided in the operation lever.